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Working on some carbs for a friend who has some seized and damaged pilot screws. The bike needs tuning and these have to come out.
Had some angle layin around the shop and made some more progress today on the machining fixture for drilling out the seized pilot screws...the carbs mounted perfectly. I made up some spacers to the tune of .600" to fill in the gap created by the carb nozzles, picked up some 35mm long bolts to secure the carbs to the fixture...they are solid, and I might not even need to use the levelers I added to the base. I will likely need to add a few more slots in the bottom of the fixture so I can secure it and bolt the fixture to the drill press table.
I took off the bracket that holds the two carbs together and used a 6mm transfer punch to locate the holes into the fixture. I plan to use this transfer punch to center punch the damaged pilot screws so the drill bits don't walk or jump around.
I also think I will start with a .250" bit and touch the face of the damages pilot screws, and impart the bit tip profile into the face...maybe I wont need to use the transfer punch...then I will have a perfect lead for subsequent drill bits.
I will start with a 3/32 and move the chain until I get to my tap drill size...a #5 I believe which is .001 below a 5.25mm, and measures .205". The brass and aluminum are soft enough, I think .001 or .0005" will allow some forgiveness.
I am sure there are a few 'steady as she goes' comments coming. I am nervous as failure here is to scrap the carb bodies...don't know what else to do.
Any suggestions?
Had some angle layin around the shop and made some more progress today on the machining fixture for drilling out the seized pilot screws...the carbs mounted perfectly. I made up some spacers to the tune of .600" to fill in the gap created by the carb nozzles, picked up some 35mm long bolts to secure the carbs to the fixture...they are solid, and I might not even need to use the levelers I added to the base. I will likely need to add a few more slots in the bottom of the fixture so I can secure it and bolt the fixture to the drill press table.

I took off the bracket that holds the two carbs together and used a 6mm transfer punch to locate the holes into the fixture. I plan to use this transfer punch to center punch the damaged pilot screws so the drill bits don't walk or jump around.
I also think I will start with a .250" bit and touch the face of the damages pilot screws, and impart the bit tip profile into the face...maybe I wont need to use the transfer punch...then I will have a perfect lead for subsequent drill bits.
I will start with a 3/32 and move the chain until I get to my tap drill size...a #5 I believe which is .001 below a 5.25mm, and measures .205". The brass and aluminum are soft enough, I think .001 or .0005" will allow some forgiveness.
I am sure there are a few 'steady as she goes' comments coming. I am nervous as failure here is to scrap the carb bodies...don't know what else to do.
Any suggestions?